Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
Consider the following relational schema: Doctor(DName,Reg_no) Patient(Pname, Disease) Assigned_To (Pname,Dname) Give expression in both Tuple calculus and Domain calculus for every of the queries:(i) Get the names of patients who are assigned to more than one doctor. (ii) Get the names of doctors who are treating patients with ‘Polio'.
Ans: (i)Tuple Calculus: {p[PName] | p ∈ PATIENT ∧ ∃a1, a2 (a1 ∈ ASSIGNED_TO ∧ a2 ∈ ASSIGNED_TO ∧p[PName] = a1[PName] ∧ a1[PName] = a2[PName] ∧ a1[DName] ≠ a2[DName])} Domain Calculus:{p | ∃p1, d1, p2, d2 (
∈ PATIENT ∧ ∈ ASSIGNED_TO ∧ ∈ASSIGNED_TO ∧ p1 = p2 ∧ d1 ≠ d2)} (ii)Tuple Calculus: {u[Dname] | u ∈ ASSIGNED_TO ∧ ∃t (t ∈ PATIENT ∧ t[Disease] = ‘Polio' ∧t[PName] = u[PName])} Domain Calculus: {d | ∃p1, p2, s2 ( ∈ ASSIGNED_TO ∧ ∈ PATIENT∧ p1 = p2 ∧ s2 = ‘Polio')}
What is Candidate Key Super Key or Candidate Key: It is such an attribute of a table that can uniquely recognize a row in a table. Generally they have unique values and can n
why are older data models are being replaced by new data models
what is the need of a log in dbms
What is deadlock? How can it be avoided? How can it be resolved once it occurs? Deadlock happens when two transactions are each waiting on a resource that the other transaction
Fragmentation: It is definite as partitioning of a relation into various fragments.Every fragment can be stored at a dissimilar site.
Difference between LEFT OUTER JOIN and RIGHT OUTER JOIN In left outer join tuples from the left-hand-side relation which do not match any tuple in the right-hand-side relation
multidimensional data model
ALTER TABLE Command : This command is used for variation of existing structure of the table in the given situation: When a new column is to be added to the table structure.
State about the Activity Diagram Activity diagrams show flow from one activity to other. It is an ongoing non atomic execution within a state machine. Activity finally results
What Command You Use What Day of the week were you born
Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd